The hydroformylation of allyl acetate is taught in the prior art. British Pat. Nos. 1,461,831 and 1,493,154, for example, teach processes for preparing butanediols. In the hydroformylation reaction, allyl acetate is reacted with a CO/H2 gas mixture in the presence of a catalyst to form 4-acetoxybutyraldehyde (ABA). The ABA may then be separated from the catalyst, e.g., by water extraction, and hydrolyzed and/or hydrogenated to form 1,4-butanediol (BDO). British Pat. No. 1,461,831 teaches the use of a cobalt or rhodium catalyst in the hydroformylation reaction. British Pat. No. 1,493,154 discloses the use of a catalyst comprising a rhodium complex containing a polymeric phosphorus compound.
One disadvantage of the hydroformylation of allyl acetate is that other co-products or byproducts are also formed in addition to the desired ABA linear product. The hydroformylation of allyl acetate typically produces some 3-acetoxy-2-methylpropionaldehyde (AMPA) branched co-product and C3 byproducts such as acetates of propylene or propane, and C4 byproducts such as butyraldehyde. Although AMPA may be hydrolyzed and/or hydrogenated to produce 2-methyl-1,3-propanediol (MPD), which is a useful material, the MPD co-product reduces the yield of BDO. Formation of C3 byproducts effectively represents another yield loss in the process which can have a severe adverse effect on the process economics.
In sum, new processes for hydroformylating allyl acetate to produce 4-acetoxybutyraldehyde are needed. Particularly valuable processes would result in high ratios of 4-acetoxybutyraldehyde to 3-acetoxy-2-methylpropionaldehyde.